Religion is also a protected class, and that's not unchangeable. Political affiliation is also a protected class in California, and it's certainly possible that it could be made so at the national level.
But in any case, the comment by M2Ys4U was making an argument based on the idea of freedom of association. I'm generally for that freedom, but making an argument from freedom of association without addressing anti-discrimination laws can at least appear opportunistic and cynical (though it may not be).
You've never heard of religious conversions? Or people losing their faith?
I think it is easier to change our beliefs about some things than others, but that has more to with how that belief relates to our other beliefs. If a particular belief is not just something we believe to be true, but is also a framework we use to make sense of the world, then new information is rarely sufficient to contradict it. With any worldview/religion/ideology, you're going to run into facts that are difficult to explain in light of it.
> You've never heard of religious conversions? Or people losing their faith?
Are these conscious though? I always assumed faith was spontaneous. You don't just read a holy book and become a believer right? Faith stems from one's upbringing and/or deeply felt religious experiences. Whereas a non-religious book that gave you new facts about a particular topic could potentially convince you to change your mind.
I think you're right that opinions are harder to change the more fundamental to one's worldview they are.
I see the change in belief as always being a two-step process:
1. Receiving and understanding new information
2. Processing and integrating that new information.
When the belief you are updating is a relatively unconnected node in the graph of beliefs, that second processing step takes almost no time. If it's heavily connected, the processing takes longer. That's why conversions often seem "spontaneous": your subconscious has been busily reworking the web of beliefs to integrate the new information, and eventually everything clicks into place and you have an epiphany.
I don't see faith as some special category of per se. To my mind, faith is simply another word for trust. The implication is simply that it is a belief you are willing to act on.
The cancel culture debate is about free speech ideals, not actual laws. Moral rights, not legal rights (these are not the same thing and the latter is not a perfect subset of the former).
Speech or opinions aren't a protected class for discrimination.
So your analogy isn't apt.